Materialism and Idealism

Materialism and Idealism

Perhaps the most basic distinction among philosophical approaches to the mind-body problem is the one that divided materialists and idealists. The materialist position is that everything is ultimately reducible to matter. From this standpoint, the thought does not really exist. Its existence is illusory; the mind is really an aspect (or function) of matter.

At the other extreme, the idealist contends that only the mind really exists (for us, at least). For all the apparent substantiality of matter, the “things” we see, touch, and hear are really nothing other than products of our mental processes (i.e., they are actually perceptual images). We can never reach beyond the envelope of conscious awareness and demonstrate the existence of any thing independent of our mind's perceptual images. So, from this standpoint, the concrete thing may not really exist, or at least it, too belongs inside the “thought bubble”.

Although these positions both appear logically tenable, the idealist position has fallen out of favor. This seems to be due to the vagaries of intellectual fashion more than anything else. Within cognitive science today, just about everyone is a materialist. But materialists come in different shapes and sizes.

Monism and Dualism

The dichotomy between monism and dualism is perhaps just as fundamental as the one between materialism and idealism, and is easily confused with it. According to the monist position, we are made of only one kind of “stuff”. In other words, mind and matter (which appear to be two things) are really reducible to one and the same thing. This might seem to be identical to the materialist position just described (and the two arguments do normally go together), but the monist position does not actually state that the singular stuff we are made of is matter. A monist could just as well claim that we really consist only of mind (thereby embracing an idealist position) or even that we are actually made of some other kind of stuff, as yet undefined, which is neither mind nor matter. In the monist position, all that counts is that the apparent distinction between mind and matter dissolves into a common something.

The dualist view – closely associated with the name of René Descartes – simply states the opposite: We are divided in our essence and are made of two kinds of stuff. Matter and mind (or body and soul) are quite irreducible to one another. Like idealism, dualism is very unfashionable nowadays. Most cognitive scientists, therefore, are materialist monists: they believe that mind and brain are ultimately reducible to a single kind of stuff, and that that stuff is physical – specifically, some property of neurons (or an aggregate of subset of neurons).

The mind can be regarded as a higher level of organization of neurons, just as water is a higher level of organization of its constituent atoms. Photo by Elena.

Reductionism, Interactionism, Other Strange Things

Materialist monism defines the relationship between two types of stuff. On this view, one type of stuff (brain tissue) is more fundamental, even more real, than the other (conscious awareness). As Dr. Crick said once “you, your joys and your sorrows, your memories and your ambitions, your sense of personal identity and free will are, in fact, no more than the behavior of a vast assembly of nerve cells” - “you” are reduced to nerve cells. The essence of Crick's reductionism resides in these words: “in fact, no more than.” Reductionism reduces one thing to another (in this case, mind to brain) and thereby explains it away. However, not all materialists are reductive.

Dualists are, by definition, nonreductive. The crux of their position is that mind and brain cannot be reduced to one another. What, then, is the nature of the relationship between two? A dualist's answer to this question determines what kind of dualist he or she is. Most dualists describe the relationship between mind and body in interactionist terms; they assert that physical events have mental effects, and vice versa. The interactionist view, then, is simply that body, and mind interact with each other. This seems perfectly plausible and appears easy to demonstrate empirically: plummeting blood sugar causes loss of consciousness (physical event causes mental event); freely deciding to move your hand causes it to move (mental event causes physical event). But when the logical underpinnings of the dualist position are spelled out, it seems less plausible: the interactionist actually claims that bodily stuff and mental stuff interact with each other. This way of putting it immediately reveals the pitfalls of almost any dualist position. How, exactly, does a thought (which has no physical properties whatever) cause the physical stuff of neurons to start firing? This violates all the known laws of physics.

Other varieties of dualism fare no better. One such well-known variety is called psychophysical parallelism. This position avoids some problems of interactionism by claiming that mental and physical events do not have a causal relationship; the two classes of event simply co-occur – they are correlated with one another. Whenever something specific happens in the brain, something equally specific happens in the mind, and vice versa. The two things occur together, in unison. If the basis of this correlation still seems mysterious, that's because it is. The parallelist does not not feel obliged to explain this linkage.

Emergence

We said above that not all materialists are reductionists. Many cognitive scientists today hold the view that the mind is an emergent property of the brain. According to this view, mind and brain are equally real, but they exist at different levels of complexity. Just as water (wet and flowing, at room temperature) emerges from a particular combination of hydrogen and oxygen and has distinctive properties of its own (properties that do not characterize hydrogen or oxygen alone), so, too, mental phenomena emerge when the neurons of the human brain are connected or activated in a particular way.

The Brain and the Inner World, Introduction to Basic Concepts. Mark Solms, Oliver Turnbull.

It is possible to find some merit in all of different philosophical positions. It is also possible, with a little effort, to make all of them look ridiculous. Photograph by Elena.